Choose the Games that You Want to Trade Between
To begin, choose the game to trade from, OR use the form below.
This page explains how to trade from Pokémon Platinum to Pokémon Diamond.
What You Need
Each player needs a Nintendo system that can play Nintendo DS games.
Before you can trade from Pokémon Platinum to Pokémon Diamond, you need to get the Pokédex from Professor Rowan in Sandgem Town, and you need to have at least two pokémon in your party.
How to Trade
Make sure that both players are using Nintendo DSes or 3DSes and are nearby. (Internet trades are no longer possible for Pokémon Diamond, Pokémon Pearl, Pokémon Platinum, Pokémon HeartGold, or Pokémon SoulSilver.)
Go to a Pokémon Center and go upstairs. Talk to the person in the middle, then say Yes when asked if you want to enter the room. Say Yes again to start DS Wireless Communication. Then say Yes to save the game, and say Yes when asked if it is OK to overwrite the previous save.
In the room, talk to the player that you want to trade with. When the menu appears, choose Trade.
Now select the pokémon that you want to trade, and choose TRADE when prompted. You will see the pokémon that the other player wants to trade. Choose YES to start the trade.